Polymers with unique electronic properties are emerging as viable alternatives to inorganic materials for creating new and improved electrical and optical systems and products. The electrical and optical systems and products may be, e.g., memory and logic devices, optical and electrical interconnects, illumination and information displays; light and energy resources, detectors, sensors, actuators, lithography systems, and the like. Electronics devices may be fabricated as chips, which include thin layers of various materials formed on top of one another. The adhesion between these layers needs to be strong enough for manufacturing integration, proper operation, and sufficient lifetime of the electronics device.
To fabricate electrical contacts to polymers, noble metals are used. Noble metals are resistant to chemical reactions, particularly to oxidation and to solution by inorganic acids. The adhesion of the polymers therefore onto noble metals, is also weak due to chemically inactive nature of the noble metal. Poor, adhesion strength of polymers onto noble metals prevents successful incorporation of the polymer during manufacturing of an electronic device, as the interface can not withstand chemical or mechanical processing, elevated or low temperatures, used to fabricate the device. The polymer can peel off the metal, crack, or both.
FIG. 1 is a side view 100 of a prior art interface between a noble metal 101 and a polymer 102 with an adhesion promoter 103. Adhesion promoter 103 produced, e.g., by Rohm & Haas, Inc; JSR, Inc.; or SRI, Inc, is an isolative material, which is different from noble metal 101 and polymer 102.
Addition of the isolative adhesion promoter 103 between the noble metal and polymer, however, significantly compromises the electrical performance of the electrical contact, which can render it unacceptable for the electronics device operation.
For the reasons described above, to fabricate, e.g., a ferroelectric memory capacitor, adhesion promoter 103 is not used at the interface between a ferroelectric polymer and a gold substrate. The interfacial adhesion measured by the four-point bend crack growth technique produces an interfacial adhesion energy less than 1.5 joules/meter^2. This value is much lower than the minimum adhesion energy required for successful processing and integration of the polymer electronics device into a semiconductor package. A device having such a low interfacial adhesion energy can not survive thermal, chemical, and mechanical stresses, e.g., high temperatures, wet cleaning, and other conditions that occur during the manufacturing and integration operations.